Hi Guys

 

This looks like a great forum

 

I currently have a 300Watt 24V Amerisolar panel, running to a 50Amp PWM Controller,  a 2 000 Watt 24V Pure Sine Wave Inverter and 4 (2 X 2) Energiser 102Ah 12V batteries.

 

Currently powering all my upstairs lights (12V new light put in), the fridge, laptops and TV.

 

Current problem is the cold effects the batteries, so I can get about 30Amps before they go below 24V (14 Degrees) so the fridge cant run the whole night.

 

The Axpert seems to be the solution

 

Here are some questions:

 

I can currently pull a max of 51Amps (Yesterday) by ensuring the solar is fully utilised during the day.

1) Does anyone know how much more i should get when switching to the MPPT module of the Axpert for 1 300 Watt Monocrystal Amerisolar panel?

 

2) If i have set the axpert to only charge batteries from solar, and told the system to switch to grid at 24V (Setting 12) and back to batteries at 26V (Setting 13). What would happen if in the morning while the batteries are at 25.5V (So still running power off grid), the power goes out. Will the unit switch back to battery power until the LVD?

 

Thanks very much

Seth

I currently have a 300Watt 24V Amerisolar panel, running to a 50Amp PWM Controller,  a 2 000 Watt 24V Pure Sine Wave Inverter and 4 (2 X 2) Energiser 102Ah 12V batteries.

 

Here are some questions:

 

I can currently pull a max of 51Amps (Yesterday) by ensuring the solar is fully utilised during the day.

1) Does anyone know how much more i should get when switching to the MPPT module of the Axpert for 1 300 Watt Monocrystal Amerisolar panel?

 

2) If i have set the axpert to only charge batteries from solar, and told the system to switch to grid at 24V (Setting 12) and back to batteries at 26V (Setting 13). What would happen if in the morning while the batteries are at 25.5V (So still running power off grid), the power goes out. Will the unit switch back to battery power until the LVD?

 

Thanks very much

Seth

 

Hi Seth

 

1) MPPT is approximately 30% more effective than PWM.

2) If the grid fails and battery voltage is still above Low DC cut-off (setting 29) the inverter will continue running.

I'm also a newbie, just wondering if another pv panel in parallel and 2 more batteries will be a better option. 

The PWM controller can handle 6 panels in parallel 6 x 8.14 = 48.84A

 

I'm also a newbie, just wondering if another pv panel in parallel and 2 more batteries will be a better option. 

The PWM controller can handle 6 panels in parallel 6 x 8.14 = 48.84A

 

The OP does not mention which PWM charge controller he uses, thus we don't know what can be connected to it i.t.o. maximum voltage & current, but the 50A charge controller should be able to handle more panels if the OP has mounting space for them.

 

If you do a rough calculation you will get 300Wp / 24V => 12.5A from the panel and charge controller at ideal light conditions. A 102Ah battery needs to be charged at about 10A (for 10 hours), that is 10A per 24V string. In this case the total current of 12.5A is divided between the 2 strings which leaves each string (battery) with 6.25A. Therefor it will take 102/6.25 => 16.3 hours to fully charge the 4 x 102Ah batteries, but remember, these calculations are for a perfect solution without any losses etc.etc. On a typical 5.5 hour (available sun) day, these batteries will not nearly be fully charged after a single day and by adding 2 more batteries the matter just gets worse. The best option here would be to increase the number of panels or to charge the batteries by means of utility- or generator power.

Thanks guys

 

Another question, will 2 X 300Watt 24V panels really give me the 25Amps from solar? (Living in JHB).

I plan of getting proabably a total of 900 Watts of panels to also assist on cloudier days. Will this have any issues with the inverter?

Another question, will 2 X 300Watt 24V panels really give me the 25Amps from solar? (Living in JHB).

I plan of getting proabably a total of 900 Watts of panels to also assist on cloudier days. Will this have any issues with the inverter?

 

Under ideal conditions you will get close to that, that is if the sun hits the panels at 90

Under ideal conditions you will get close to that, that is if the sun hits the panels at 90

If the combined VOC exceeds the controller, will the controller just limit the input? I think Voc on this panel is 45V and Imp is 8.18, thus on 3 panels VOC would be 135 and Imp 24.54. How would the system react to this? System will be in parallel, so will the Voc be Okay?

 

No, the Voc may not exceed the charge controller's max Vin. I'm not sure what you mean by "system will be in parallel"? If you parallel the panels the Voc will still be 45V, and the total current will be 3 x 8.18A; if you connect the panels in series the Voc will be 45 x 3 and the current will be 8.18A. What is the charge controller's max V_IN and max I_IN?

The panels will be in parallel as they are already at the required voltage for the system.

 

As the maximum solar current is 25Amps, and I have read that you should have a small margin between panels and controller in case their is a spike in current, would i be able to attach a 200 Watt panel in parallel with the 2 300 Watt panels, to give me a theoretical maximum Amps input of 20 in order to protect the controller? Would this act like a 800 Watt st=ystem or would puting a smaller panel limit anything on the other panels?

 

Axpert 3k 24V has 30-66 Vdc MPPT Pv Array Range and a Max PV Array Open Circuit voltage of 75Vdc Max.

 

I dont think it is worth getting the plus model as my power requirements are quite low and i dont plan on using any really large appliances on it. (Maybe washing machine during the day when excess power is available and batteries are fully charged)

 

It will not be wired into the DB board currently, and if i do, it will probably be for downstairs light circuit only as i plan on running extension cables to reach the TV, fridge etc...

 

My battery bank will probably reach a max of 400 Ah @ 24V as this will give me enough power at night for most of what i need to do.

 

Any other suggestions for what i plan on doing?

The panels will be in parallel as they are already at the required voltage for the system.

 

As the maximum solar current is 25Amps, and I have read that you should have a small margin between panels and controller in case their is a spike in current, would i be able to attach a 200 Watt panel in parallel with the 2 300 Watt panels, to give me a theoretical maximum Amps input of 20 in order to protect the controller? Would this act like a 800 Watt st=ystem or would puting a smaller panel limit anything on the other panels?

 

Axpert 3k 24V has 30-66 Vdc MPPT Pv Array Range and a Max PV Array Open Circuit voltage of 75Vdc Max.

 

I dont think it is worth getting the plus model as my power requirements are quite low and i dont plan on using any really large appliances on it. (Maybe washing machine during the day when excess power is available and batteries are fully charged)

 

It will not be wired into the DB board currently, and if i do, it will probably be for downstairs light circuit only as i plan on running extension cables to reach the TV, fridge etc...

 

My battery bank will probably reach a max of 400 Ah @ 24V as this will give me enough power at night for most of what i need to do.

 

Any other suggestions for what i plan on doing?

 

The cells in a PV panel are connected in series and therefor the Voc and Vmpp of a 200W, 250W, 300W etc. PV panel will all differ and it is not a good idea to connect different types of panels in parallel. I would suggest to rather connect 3 x 300W panels in parallel - the charge controller will only use as much current as it requires at any given time and if your panels are mounted at a fixed angle you will in any case not get max current all the time.

The cells in a PV panel are connected in series and therefor the Voc and Vmpp of a 200W, 250W, 300W etc. PV panel will all differ and it is not a good idea to connect different types of panels in parallel. I would suggest to rather connect 3 x 300W panels in parallel - the charge controller will only use as much current as it requires at any given time and if your panels are mounted at a fixed angle you will in any case not get max current all the time.

 

Sounds good.

 

WIll the inverter be able to limit the current to 25 Amps should it exceed 25 without any damage?

Sounds good.

 

WIll the inverter be able to limit the current to 25 Amps should it exceed 25 without any damage?

 

The panels cannot push more current than required, the inverter will pull what it needs. Compare it to a battery: your 100Ah 12V battery can supply maybe a 1000 amps or more for a very short period of time, but if you connect a 12V 12W bulb to the battery, the bulb will only draw 1A from the battery - not 1000A.

Another question:

 

I recently had an Axpert 5000VA/4000W inverter installed. When Solar first (program 1) is selected the inverter starts to dip every few seconds when the battery voltage? come down to approx. 49V. It keeps on dipping even after the battery voltage went below 48V, my voltage back setting (program 12)

When the inverter is set at Utility first it start to dip virtually from the start and my battery voltage tend to go down.

Some of the other settings that may be relevant is: Max charging current = 50A (program 2); Input voltage range = appliance (program 3); Max utility charging current = 30A (program 11) and Charging source priority = Solar and utility (program 16).

Could it be that I have utility supply problems to the inverter, supply line to thin or to long

I don't know what you mean by "the inverter starts to dip".

 

It's unusual to want to select SOL for parameter 1 (Output Source Priority). This mode seems to be intended for a solar powered UPS (Uninterruptable Power Supply), where the battery is kept fully charged and not used unless both the utility and the solar (PV) are not present. You probably want SbU mode (Solar, then battery, then Utility if all else fails). Or if you are in an off-grid situation and the utility is actually a generator, then you want UtI mode (Utility first; when the generator is present, use it).

 

BTW, I'm a noob at this forum. I don't know how to make my replies come after the quote. I see others manage it... what's the secret? [ Edit: now the quotation disappeared altogether. I can use the "quote" facility, but then it doesn't have the author's name. Like below. ]

 

When Solar first (program 1) is selected the inverter starts to dip every few seconds...

 

 

 

I don't know what you mean by "the inverter starts to dip".

 

It's unusual to want to select SOL for parameter 1 (Output Source Priority). This mode seems to be intended for a solar powered UPS (Uninterruptable Power Supply), where the battery is kept fully charged and not used unless both the utility and the solar (PV) are not present. You probably want SbU mode (Solar, then battery, then Utility if all else fails). Or if you are in an off-grid situation and the utility is actually a generator, then you want UtI mode (Utility first; when the generator is present, use it).

 

BTW, I'm a noob at this forum. I don't know how to make my replies come after the quote. I see others manage it... what's the secret? [ Edit: now the quotation disappeared altogether. I can use the "quote" facility, but then it doesn't have the author's name. Like below. ]

 

 

 

When you click on 'Quote' the cursor appears at the bottom, are you clicking above the quote ?.

 

@janet

Dip - are you referring to the 220V AC voltage ?.

When you click on 'Quote' the cursor appears at the bottom, are you clicking above the quote ?.

 

I start typing below the quote. But sometimes when I remove text from the quote (edit: from inside the quote box; I usually don't want the entire previous post quoted), it puts my text above the quote, and doesn't seem to let me get below the quote again.

 

It didn't do it this time.

I start typing below the quote. But sometimes when I remove text from the quote (edit: from inside the quote box; I usually don't want the entire previous post quoted), it puts my text above the quote, and doesn't seem to let me get below the quote again.

 

It didn't do it this time.

There are hidden characters behind it all that are accidentally deleted or moved.

If it moves in a unexpected manner, undo and start again. CTRL-Z for undo.

Until you find the sweet spot.

When you click on 'Quote' the cursor appears at the bottom, are you clicking above the quote ?.

 

@janet

Dip - are you referring to the 220V AC voltage ?.

Thanks, I will test SbU mode to see if it helps. By dipping I mean that when the inverter is suppose to switch to 220V AC (Eskom) the unit switch off and immediately on again, as if it is hunting for Eskom and cannot find it.

@janet - which Axpert inverter? 5kva or smaller?

My immediate thoughts are that it maybe overloaded and going to bypass to Eskom, and if it is really overloaded, it will trip out and then a few seconds later try to auto restart if this setting is enabled ?

If you are running a 3kva 2000watt Axpert I think it's a good chance this could be the case?

@janet

Sorry just saw above you are talking about a 5kva - change the appliance setting to ups? From the manual I understand when you choose appliance it will drop to well below 220volts, possibly as low as 90v and try to carry the load.

I can't see where one would use this, maybe for lights only, but most home devices and anything with a chip in it would have a problem with this. I think it tells the Axpert to generate a modified sine wave to

Conserve power, but it's not good for motors and sensitive electronics.

Read up on this and I think you will agree the ups setting is best

@janet

Sorry just saw above you are talking about a 5kva - change the appliance setting to ups? From the manual I understand when you choose appliance it will drop to well below 220volts, possibly as low as 90v and try to carry the load.

I can't see where one would use this, maybe for lights only, but most home devices and anything with a chip in it would have a problem with this. I think it tells the Axpert to generate a modified sine wave to

Conserve power, but it's not good for motors and sensitive electronics.

Read up on this and I think you will agree the ups setting is best

...  - change the appliance setting to ups? From the manual I understand when you choose appliance it will drop to well below 220volts, possibly as low as 90v and try to carry the load.

Configuration parameter 03 (AC input voltage range) is about the range of AC voltage that the inverter will accept. If it doesn't accept the input, it won't switch to it (I think the AC icon on the LCD display will flash). It either takes it or it doesn't. If it takes it, it will power the loads by connecting the AC input to the loads via an internal relay. So unless Eskom is 90 VAC, the output should never be 90 VAC.

 

It does sound like there is something wrong with the installation. You mention battery voltage of 49 and 48 V; that doesn't sound healthy unless the battery is small and under load, or at a quite low state of charge. But I'm rather rusty on lead acid batteries, and have never used them on a large system.

@janet

Sorry just saw above you are talking about a 5kva - change the appliance setting to ups? From the manual I understand when you choose appliance it will drop to well below 220volts, possibly as low as 90v and try to carry the load.

I can't see where one would use this, maybe for lights only, but most home devices and anything with a chip in it would have a problem with this. I think it tells the Axpert to generate a modified sine wave to

Conserve power, but it's not good for motors and sensitive electronics.

Read up on this and I think you will agree the ups setting is best

Thanks, I have changed to UPS, make a lot of sense. The problem only become visible when my battery voltage approach the  point back to Eskom voltage (setting 12). I will test it tonight when I will run my batteries down to the voltage at which it have to change over to Eskom. My load is running only at about 25% and it is not overloading.

Arandoza, on 25 Jan 2016 - 7:10 PM, said:

@janet

Sorry just saw above you are talking about a 5kva - change the appliance setting to ups? From the manual I understand when you choose appliance it will drop to well below 220volts, possibly as low as 90v and try to carry the load.

I can't see where one would use this, maybe for lights only, but most home devices and anything with a chip in it would have a problem with this. I think it tells the Axpert to generate a modified sine wave to
Conserve power, but it's not good for motors and sensitive electronics.

Read up on this and I think you will agree the ups setting is best

 

Thanks, I have changed to UPS, make a lot of sense. The problem only become visible when my battery voltage approach the  point back to Eskom voltage (setting 12). I will test it tonight when I will run my batteries down to the voltage at which it have to change over to Eskom. My load is running only at about 25% and it is not overloading.

I am stil sitting with a situation where my inverter starts to "hunt" for Eskom power when it reach the point back to Eskom (utility) - (setting 12) battery voltage. As a last resort I linked the inverter with my laptop with the WatchPower monitoring software that is supplied with the Axpert. The software indicate a LINE_FAIL warning every time the inverter try to switch over to Eskom power. The problem is visible in line and battery mode.

Any ideas would help since with my limited knowledge I am at a dead end.

Hi Janet,

I have the same issue when running the inverter with resistive loads, like when using an iron or when the dishwasher or washing machine is running and starts to heat the water.

The problem occurs while the inverter is running on battery and the battery and or Pv panels cannot supply enough power, so the inverter switches back to Eakom, and my earth leakage trips. However if I run these items while the inverter is running from Eskom, no problem earth Leakage tripping.

My inverter gets its mains after the earth leakage and from what I understand the inverter should get its Eskom supply before the earth leakage to prevent this problem, also one must have a earth leakage on your inverter db board or risk of electrocution

I have always had this problem, but only on resistive loads it seems, I have never connected a microwave and run it for 20min to see if it causes the same type of problem when running from solar. It may do?

I need to change my supply connection to resolve this, I think but have not yet done so.

Hope this helps and maybe a few of the experts can confirm my thinking above?